fix(#1264): preserve portable standalone launch

docs/ADMIN-GUIDE/operations/fleet-unattended-first-start.md

@@ -27,7 +27,8 @@ The fleet path never falls back to an interactive wizard. It exits nonzero befor
 when:
 
 - `MOSAIC_AGENT_NAME` is not an exact roster member;
-- an ambient `MOSAIC_AGENT_CLASS` disagrees with that member's canonical class;
+- a defined ambient `MOSAIC_AGENT_CLASS` is blank/whitespace or disagrees with that member's
+  canonical class;
 - a missing destination has no safe regular default source;
 - a source or existing destination is a symlink (including dangling), directory, unavailable, or over the bounded size;
 - the fleet communications helper/roster cannot be validated; or
@@ -56,8 +57,8 @@ The build leg is load-bearing: `dist/` is ignored, so a direct Vitest invocation
 absent or stale CLI output. The gate runs the exact-source built CLI in subprocesses with piped stdin,
 temporary homes, a canonical fixture roster, fake runtime/broker executables, and no provider call. It
 covers no-TTY launch, exact identity,
-private modes, no-clobber, missing/symlink defaults, unknown members, class mismatch,
+private modes, no-clobber, missing/symlink defaults, unknown members, blank/mismatched class,
-standalone wizard preservation, and concurrent first start.
+portable standalone composition/wizard preservation, and concurrent first start.
 
 Do not use this fixture as proof that a real provider credential is present or that a package has
 been deployed. Those require separate environment-specific evidence.

docs/DEVELOPER-GUIDE/architecture/fleet-first-start-identity.md

@@ -16,8 +16,8 @@ The fix remains at `checkSoul()` and does not add flags to `yolo`, fleet command
 
 1. A present, nonblank, whitespace-exact `MOSAIC_AGENT_NAME` selects the fleet path.
 2. `resolveFleetIdentity()` must resolve that exact member through the existing roster/helper
-   boundary, and any ambient `MOSAIC_AGENT_CLASS` must canonicalize to the roster class, before any
+   boundary, and any defined `MOSAIC_AGENT_CLASS` (including blank/whitespace) must canonicalize to
-   identity seed.
+   the roster class, before any identity seed. Only undefined means absent.
 3. `lstatSync()` preflights every destination directory entry without following links, so a dangling
    link is rejected before its counterpart can be published.
 4. Safe bounded snapshots are read from only the missing contracts under `defaults/`.
@@ -26,10 +26,12 @@ The fix remains at `checkSoul()` and does not add flags to `yolo`, fleet command
    concurrent seat or operator won; the existing path is preserved and revalidated.
 7. Temporary files are removed, and both installed contracts are re-opened through the no-symlink
    secure-file reader before launch continues.
-8. `composeContract()` independently re-resolves the roster, securely reads `USER.md` through a
+8. `composeContract()` independently re-resolves the roster, securely reads fleet `USER.md` through
-   descriptor at the point of use, and injects exact member identity and communications data.
+   a Linux descriptor at the point of use, and injects exact member identity and communications data.
 
-A standalone launch with no `MOSAIC_AGENT_NAME` retains the interactive wizard.
+A standalone launch with no `MOSAIC_AGENT_NAME` retains the portable tolerant USER read and the
+interactive wizard. Fleet-only no-follow enforcement must not make supported standalone macOS
+composition depend on Linux `/proc` descriptor traversal.
 
 ## Identity and authority
 
@@ -42,9 +44,9 @@ not the source of a fleet seat's identity. The canonical roster controls:
 - tmux socket and helper target; and
 - communications generation.
 
-An unknown/padded ambient name or mismatched ambient class fails before any file is seeded. This
+An unknown/padded ambient name, mismatched class, or explicitly blank/whitespace class fails before
-avoids replacing the interactive wall with a fleet of indistinguishable or ambiently invented
+any file is seeded. This avoids replacing the interactive wall with a fleet of indistinguishable or
-identities.
+ambiently invented identities.
 
 ## Concurrency and filesystem properties
 
@@ -64,8 +66,9 @@ no-TTY subprocess, not a direct wizard test. The package `test:vitest` gate buil
 Vitest, while the clean-checkout command builds its workspace dependencies first, so ignored
 `dist/cli.js` cannot be absent or stale. A fake lease launcher records whether execution reached the
 runtime boundary and captures the composed prompt.
-Positive and negative cases prove the check can both proceed and refuse. Composition coverage also
+Positive and negative cases prove the check can both proceed and refuse. Fleet composition coverage
-replaces a previously validated `USER.md` with an external symlink and proves point-of-use refusal.
+replaces a previously validated `USER.md` with an external symlink and proves point-of-use refusal;
+a standalone unreadable-optional-USER case proves the portable tolerant branch remains separate.
 
 Real Pi authentication and provider task execution remain environment tests, not claims of this
 fixture.

docs/USER-GUIDE/workflows/fleet-unattended-first-start.md

@@ -25,8 +25,8 @@ base. The canonical roster row supplies each seat's exact name, class, peers, so
 
 ## Operator behavior
 
-A normal standalone launch without a fleet identity still uses the interactive wizard when
+A normal standalone launch without a fleet identity retains its portable configuration path and still
-`SOUL.md` is absent:
+uses the interactive wizard when `SOUL.md` is absent:
 
 ```bash
 mosaic pi
@@ -38,8 +38,8 @@ A roster-owned seat may be started without attaching to its pane:
 mosaic fleet start <exact-roster-name>
 ```
 
-Mosaic refuses before runtime execution if the requested member is absent, its ambient class
+Mosaic refuses before runtime execution if the requested member is absent, its explicitly supplied
-conflicts with the roster, a required default is missing or unsafe, or an existing identity contract
+ambient class is blank or conflicts with the roster, a required default is missing or unsafe, or an existing identity contract
 is not a safe regular file. Repair the named component and retry the same exact roster member; do not
 copy another seat's personalized identity.
 

docs/reports/code-review/1264-code-review.md

@@ -71,6 +71,25 @@ Result: risk `none`, confidence `0.93`, 9 files, no critical/high/medium/low fin
 could not run Vitest because Vite attempted to create a temporary config artifact on its read-only
 mount (`EROFS`); executor-owned focused and full results are recorded in the QA report.
 
+## Second exact-head review
+
+Daphne reviewed exact head `9dc90be7e13b1cd609f6df97d43d890ef5392ca0` and filed Gitea review
+ID 169 as `REQUEST_CHANGES`. Review 169 confirmed all review-168 closures, then found:
+
+1. the new point-of-use reader was Linux-only but had been applied to every standalone USER read,
+   breaking supported non-fleet macOS composition; and
+2. explicit blank/whitespace `MOSAIC_AGENT_CLASS` was treated as absent and could seed before
+   runtime, while only undefined should mean absent.
+
+Red-first remediation preserves legacy `readOptional()` for standalone composition, keeps descriptor
+no-follow consumption fleet-only, moves the replacement-symlink case under a valid fleet identity,
+and rejects defined blank/whitespace classes before seeding. Three blank-class CLI cases and one
+tolerant standalone composition case failed before the source change and pass after it.
+
+Review-169 remediation code review approved at confidence `0.90` (4 files, no findings). Security
+review reported risk `none` at confidence `0.90` (4 files, no findings). The review sandbox retained
+its known Vite `EROFS` limitation; executor-owned tests are in the QA report.
+
 ## Remaining review gate
 
 Daphne must re-review the next exact pushed head. This report cannot record that future verdict

docs/reports/documentation/1264-documentation-checklist.md

@@ -25,6 +25,8 @@
 
 - [x] Initial padded-name finding remediated and automated re-review approved.
 - [x] Daphne formal review ID 168 completed on exact first head `43fa0477` and requested changes.
-- [x] Four formal-review groups reproduced red and remediated; automated remediation code/security
+- [x] Four review-168 groups reproduced red and remediated; automated reviews are clean.
-      reviews are clean.
+- [x] Daphne review ID 169 completed on exact head `9dc90be7` and confirmed review-168 closures.
-- [ ] Daphne exact-remediation-head re-review completed after push (Fred/goals excluded).
+- [x] Review-169 standalone-portability and blank-class blockers reproduced red and remediated;
+      automated reviews are clean.
+- [ ] Daphne exact-second-remediation-head re-review completed after push (Fred/goals excluded).

docs/reports/qa/2026-08-16-1264-unattended-first-start.md

@@ -1,7 +1,7 @@
 # #1264 Unattended Fleet First-Start Verification
 
-> Status: **IN PROGRESS — review remediation complete locally; push/re-review pending** | Executor:
+> Status: **IN PROGRESS — review-169 remediation complete locally; push/re-review pending** |
-> goals | Date: 2026-08-16 | Target: isolated local fixtures only
+> Executor: goals | Date: 2026-08-16 | Target: isolated local fixtures only
 
 ## Objective
 
@@ -44,7 +44,7 @@ executables.
 | ---------------------------------------------------------------------- | --------------------------------------------------------------- | ----------------------------- |
 | No-TTY fleet first start avoids wizard and reaches runtime             | Exact-source built CLI with piped stdin                         | CLI GREEN                     |
 | Missing top-level identity files are initialized from shipped defaults | Exact-byte and `0600` assertions                                | CLI + filesystem GREEN        |
-| Exact seat identity remains roster-owned                               | Captured argv; name/class mismatch no-side-effect refusals      | CLI GREEN                     |
+| Exact seat identity remains roster-owned                               | Captured argv; mismatched/blank class no-side-effect refusals   | CLI GREEN                     |
 | Existing operator identity is never overwritten                        | Custom bytes/mode with defaults removed                         | CLI + filesystem GREEN        |
 | Concurrent/repeated first start is safe                                | Four parallel CLIs plus repeated launch                         | CLI GREEN                     |
 | Missing/unsafe defaults and destinations fail before partial mutation  | Missing, target/dangling symlink, oversized, invalid-root cases | Filesystem/CLI GREEN          |
@@ -85,7 +85,18 @@ passed:
 3. dangling `USER.md` allowed `SOUL.md` to be published before refusal; and
 4. replacing a securely validated `USER.md` with an external symlink was followed by composition.
 
-This establishes that all four reviewer findings were observable on the pushed implementation.
+This establishes that all four review-168 findings were observable on the pushed implementation.
+
+Daphne's review ID 169 then found two more exact-head failures at `9dc90be7`. Before production
+changes, four new assertions failed:
+
+1. standalone composition routed an unreadable optional `USER.md` through the Linux-only descriptor
+   reader instead of the legacy portable tolerant path; and
+2. explicit `MOSAIC_AGENT_CLASS` values `""`, `" "`, and tab were treated as absent, seeded both
+   identity files, and reached runtime.
+
+The replacement-symlink case was also moved under a valid roster identity so it tests the fleet-only
+security boundary rather than standalone behavior.
 
 ## Final GREEN
 
@@ -105,16 +116,17 @@ env -u DATABASE_URL sh -c '
 '
 ```
 
-Exit `0`: `6/6` files, `124/124` tests.
+Exit `0`: `6/6` files, `128/128` tests.
 
-- 12 real-CLI/no-TTY tests cover exact roster name/class, byte-equal `0600` seeds, no-clobber,
+- 15 real-CLI/no-TTY tests cover exact roster name/class, byte-equal `0600` seeds, no-clobber,
-  partial seed, missing/symlink defaults, unknown/padded/blank name, mismatched class, standalone
+  partial seed, missing/symlink defaults, unknown/padded/blank name, mismatched or explicitly blank
-  wizard preservation, and four concurrent starts.
+  class, standalone wizard preservation, and four concurrent starts.
 - 12 direct filesystem tests cover complete publication, existing operators, idempotence, source
   prevalidation, target and dangling destination links, invalid roots, oversized input, and
   unexpected link errors.
-- Composition coverage deterministically replaces validated `USER.md` with an external symlink and
+- Composition coverage deterministically replaces a valid fleet seat's validated `USER.md` with an
-  requires refusal at point of use.
+  external symlink and requires refusal at point of use. A separate standalone case proves tolerant
+  optional composition remains outside the Linux-only fleet reader.
 
 Full package gate (which rebuilds Mosaic itself after the clean-checkout dependency build):
 
@@ -122,13 +134,13 @@ Full package gate (which rebuilds Mosaic itself after the clean-checkout depende
 env -u DATABASE_URL pnpm --filter @mosaicstack/mosaic run test:vitest
 ```
 
-Exit `0`: `88/88` files, `1,573/1,573` tests.
+Exit `0`: `88/88` files, `1,577/1,577` tests.
 
 Focused helper + point-of-use coverage:
 
 ```text
-2 files, 52/52 tests
+2 files, 53/53 tests
-Statements 97.97% | Branches 88% | Functions 100% | Lines 97.97%
+Statements 97.84% | Branches 91.66% | Functions 100% | Lines 97.84%
 Exit 0
 ```
 
@@ -164,9 +176,14 @@ because this checkout prohibits the PostgreSQL-dependent gateway isolation path.
 - Codex security review of the remediation: risk `none`, confidence `0.93`, 9 files, no findings.
   Its sandbox could not execute Vitest because Vite attempted a write on a read-only mount; the
   executor-owned results above are the test evidence.
-- Daphne formal review ID 168 at exact head `43fa0477`: `REQUEST_CHANGES`, four blocking groups. All
+- Daphne formal review ID 168 at exact head `43fa0477`: `REQUEST_CHANGES`, four blocking groups; all
-  four have red-first regressions and local green remediation. Re-review of the next pushed exact
+  closed by review 169.
-  head is necessarily pending until that head exists.
+- Daphne formal review ID 169 at exact head `9dc90be7`: `REQUEST_CHANGES`, two blocking groups
+  (standalone portability and explicit blank class). Both now have red-first regressions and local
+  green remediation.
+- Codex review of review-169 remediation: `approve`, confidence `0.90`, 4 files, no findings.
+- Codex security review of review-169 remediation: risk `none`, confidence `0.90`, 4 files, no
+  findings. Exact-new-head Daphne re-review is pending until that head is pushed.
 
 ## CI evidence and external blocker
 
@@ -183,7 +200,9 @@ FAIL: host provides 'pi' in the system path; missing-binary cases are not measur
 That line comes from the inherited `test-start-agent-session.sh` CI-fit guard, not #1264. Fred filed
 the correction as PR #1270. Its pipeline 2448 is terminal green and proves the four formerly masked
 suites execute, but #1270 is not merged, so `next` still carries the failing chain. A new #1268
-pipeline is pending the remediation push. Terminal-green #1268 CI is not claimed.
+pipeline 2449 at `9dc90be7` reproduced the same single inherited `FAIL:` after Mosaic passed
+`1,573/1,573`. A new pipeline is pending the review-169 remediation push. Terminal-green #1268 CI is
+not claimed.
 
 PR #1268's envelope was read back as `user.login=mos-dt-0`; its commit is explicitly authored and
 committed by `goals <[email protected]>`. No goals Gitea login exists on this host, and no

docs/scratchpads/1264-unattended-first-start.md

@@ -7,13 +7,14 @@
 - Branch: `fix/1264-fleet-unattended-first-start`
 - Base: `origin/next@476db12b92971634b67fd2057b7577ee5894e449`
 - First pushed head: `43fa0477877e0d0f110da8d11c3033b40ddeb191`
-- Current remediation worktree: `/var/home/jason.woltje/agent-work/1264-review-remediation`
+- Current remediation worktree: `/var/home/jason.woltje/agent-work/1264-review2-remediation`
 - Coordinator: Fred; reviewer must be neither Fred nor this implementation seat.
 - `docs/TASKS.md` is orchestrator-owned and is not modified by this worker.
 
-The original `/var/home/jason.woltje/agent-work/1264-unattended-first-start` worktree was removed
+The original `/var/home/jason.woltje/agent-work/1264-unattended-first-start` and first remediation
-without force after its pushed head and clean state were verified. The Fred-authorized plain-Git
+worktrees were removed without force after each pushed head and clean state were verified. The
-worktree exception was reused for exact-head review remediation because `/src` remains unavailable.
+Fred-authorized plain-Git worktree exception was reused for exact-head review remediation because
+`/src` remains unavailable.
 
 ## Objective
 
@@ -37,14 +38,16 @@ preserving the standalone interactive wizard.
 
 - PRD IDs: `FCM-REQ-12`, `AC-FCM-10`; `FCM-REQ-11` is reserved by #1256.
 - A present fleet name must be nonblank, whitespace-exact, and resolve through the canonical roster.
-- Any ambient class must canonicalize to the roster class before mutation.
+- Any defined ambient class, including blank/whitespace, must canonicalize to the roster class before
+  mutation; only undefined means absent.
 - Preflight all destination directory entries with no-follow existence semantics so dangling links
   fail before counterpart publication.
 - Seed only missing top-level files from bounded regular defaults with owner-private, atomic,
   no-clobber hard links.
 - Generic defaults are behavior, not identity or authority.
-- Securely consume `USER.md` through a descriptor at composition time.
+- Securely consume fleet `USER.md` through a Linux descriptor at composition time.
-- Standalone missing identity retains the wizard.
+- Standalone composition retains the portable tolerant USER read and missing identity retains the
+  wizard.
 
 ## Progress
 
@@ -54,9 +57,11 @@ preserving the standalone interactive wizard.
 - [x] Initial automated review finding (padded name before write) remediated.
 - [x] Commit `43fa0477` pushed; PR #1268 opened against `next`; original worktree removed cleanly.
 - [x] Daphne formal review ID 168 completed on exact first head: `REQUEST_CHANGES` with four groups.
-- [x] All four groups reproduced red before remediation and now pass locally.
+- [x] All four review-168 groups reproduced red before remediation and passed at `9dc90be7`.
-- [x] Remediation Codex review approved; remediation security review risk `none`.
+- [x] Daphne review ID 169 completed on `9dc90be7`: review-168 closures confirmed; two new blockers.
-- [ ] Commit/push remediation with explicit goals author/committer; verify remote object/content.
+- [x] Review-169 portability and blank-class blockers reproduced red and now pass locally.
+- [x] Review-169 Codex review approved; security review risk `none`.
+- [ ] Commit/push second remediation with explicit goals author/committer; verify remote object/content.
 - [ ] Daphne exact-new-head re-review.
 - [ ] Terminal #1268 CI. Pipeline 2445's only `FAIL:` was the inherited Pi-PATH CI-fit guard; PR
   #1270's pipeline 2448 is green, but #1270 is not merged.
@@ -73,13 +78,15 @@ and never created the fake runtime-boundary capture.
 
 Against exact first-head production code, four new tests failed while 1,568 existing tests passed:
 class mismatch mutated before refusal; each dangling destination left its counterpart; and a
-replacement `USER.md` symlink was consumed by composition.
+replacement `USER.md` symlink was consumed by composition. Review-169 RED then proved standalone
+composition hit the Linux-only reader and three explicit blank/whitespace class cases seeded and
+launched.
 
 ### Final local GREEN
 
-- Exact-source focused gate: `6/6` files, `124/124` tests.
+- Exact-source focused gate: `6/6` files, `128/128` tests.
-- Full exact-source Mosaic Vitest: `88/88` files, `1,573/1,573` tests.
+- Full exact-source Mosaic Vitest: `88/88` files, `1,577/1,577` tests.
-- Helper + point-of-use coverage: `52/52`; 97.97% statements/lines, 88% branches, 100% functions.
+- Helper + point-of-use coverage: `53/53`; 97.84% statements/lines, 91.66% branches, 100% functions.
 - Root preflight passed; typecheck `45/45`, lint `25/25`, build `25/25`.
 - Initial targeted shell gates passed: start-agent-session, install migration `21/21`, init-RCE.
 - Local aggregate framework shell stops at operator-global Pi `0.84.2` versus measured `0.84.1`.
@@ -90,8 +97,8 @@ The full evidence and command boundaries are in
 
 ## Review / delivery notes
 
-- Codex remediation review: approve, confidence `0.88`, no findings.
+- Review-168 remediation Codex review: approve `0.88`; security risk `none` `0.93`.
-- Codex remediation security review: risk `none`, confidence `0.93`, no findings.
+- Review-169 remediation Codex review: approve `0.90`; security risk `none` `0.90`.
 - PR envelope reads `mos-dt-0`; the commit reads goals/goals. No goals Gitea principal exists on this
   host, so no other principal will be borrowed. Tracked in #1272.
 - PR #1270 is pushed, not merged. Do not represent `next` or #1268 CI as green until measured.

packages/mosaic/src/commands/compose-contract.spec.ts

@@ -334,7 +334,22 @@ describe('composeContract — overlay composer', () => {
     }
   });
 
-  it('refuses a USER.md replacement symlink at the point of composition', () => {
+  it('refuses a fleet USER.md replacement symlink at the point of composition', () => {
+    mkdirSync(join(fixture.home, 'fleet'), { recursive: true });
+    writeFileSync(
+      join(fixture.home, 'fleet', 'roster.yaml'),
+      [
+        'version: 1',
+        'transport: tmux',
+        'agents:',
+        '  - name: exact-user-seat',
+        '    runtime: pi',
+        '    class: worker',
+        '',
+      ].join('\n'),
+    );
+    process.env['MOSAIC_AGENT_NAME'] = 'exact-user-seat';
+    process.env['MOSAIC_AGENT_CLASS'] = 'worker';
     writeFileSync(join(fixture.home, 'defaults', 'SOUL.md'), '# Generic soul\n');
     writeFileSync(join(fixture.home, 'defaults', 'USER.md'), '# Generic user\n');
     expect(seedFleetIdentityDefaults(fixture.home)).toEqual(['SOUL.md']);
@@ -351,6 +366,17 @@ describe('composeContract — overlay composer', () => {
     expect(readFileSync(external, 'utf8')).toBe('UNSAFE-REPLACEMENT-USER-CONTENT\n');
   });
 
+  it('preserves tolerant standalone composition when optional USER.md is unreadable', () => {
+    const userPath = join(fixture.home, 'USER.md');
+    rmSync(userPath);
+    mkdirSync(userPath);
+
+    const out = composeContract('pi', fixture.home);
+
+    expect(out).toContain(AGENTS);
+    expect(out).not.toContain('# User Profile');
+  });
+
   it.each(['claude', 'codex', 'opencode', 'pi'] as const)(
     'never injects installed TOOLS.md through a target symlink for %s',
     (runtime) => {

packages/mosaic/src/commands/fleet-first-start-identity.ts

@@ -51,12 +51,11 @@ function installedEntryExists(path: string): boolean {
   }
 }
 
-/** Secure point-of-use read for a top-level identity contract. */
+/** Secure fleet point-of-use read for a top-level identity contract. */
-export function readOptionalInstalledIdentityContract(
+export function readInstalledIdentityContractAtPointOfUse(
   mosaicHome: string,
   entry: (typeof FLEET_IDENTITY_DEFAULTS)[number],
-  required: boolean = false,
+): Buffer {
-): Buffer | undefined {
   const configuredPath = join(mosaicHome, entry);
   try {
     // Preserve the launcher's established support for a symlinked Mosaic home,
@@ -68,7 +67,6 @@ export function readOptionalInstalledIdentityContract(
       maxBytes: MAX_IDENTITY_CONTRACT_BYTES,
     }).content;
   } catch (error: unknown) {
-    if (!required && isFilesystemError(error, 'ENOENT')) return undefined;
     throw unsafeIdentityError('installed', configuredPath, error);
   }
 }

packages/mosaic/src/commands/launch-first-start.spec.ts

@@ -317,6 +317,23 @@ describe('fleet unattended first start (#1264)', () => {
     expect(existsSync(join(fixture.mosaicHome, 'USER.md'))).toBe(false);
   });
 
+  it.each(['', ' ', '\t'])(
+    'refuses explicit blank ambient fleet class %j before seeding',
+    (agentClass: string) => {
+      const fixture = createGreenfieldFixture();
+
+      const result = launchSync(fixture, { agentClass });
+      const output = outputOf(result);
+
+      expect(result.status, output).toBe(1);
+      expect(output).toContain('Refusing split identity authority');
+      expect(output).not.toContain('Running setup wizard');
+      expect(existsSync(fixture.capturePath)).toBe(false);
+      expect(existsSync(join(fixture.mosaicHome, 'SOUL.md'))).toBe(false);
+      expect(existsSync(join(fixture.mosaicHome, 'USER.md'))).toBe(false);
+    },
+  );
+
   it.each([' unattended-seat', 'unattended-seat ', ''])(
     'refuses non-exact ambient fleet name %j before seeding',
     (agentName: string) => {

packages/mosaic/src/commands/launch.ts

@@ -31,7 +31,7 @@ import { readPersonaContractBlock } from '../fleet/persona-contract.js';
 import { canonicalizeRoleClass } from './fleet-personas.js';
 import { launchClaudex, type ClaudexHarnessAdapter } from './claudex.js';
 import {
-  readOptionalInstalledIdentityContract,
+  readInstalledIdentityContractAtPointOfUse,
   seedFleetIdentityDefaults,
 } from './fleet-first-start-identity.js';
 import { runLeaseEnforcementDoctorCheck } from './lease-doctor-check.js';
@@ -236,7 +236,7 @@ function checkRuntime(cmd: string): void {
 
 function assertAmbientFleetClassMatches(canonicalName: string, canonicalClass: string): void {
   const configuredClass = process.env['MOSAIC_AGENT_CLASS'];
-  if (!configuredClass?.trim()) return;
+  if (configuredClass === undefined) return;
 
   const ambientClass = canonicalizeRoleClass(configuredClass).canonicalClass;
   if (ambientClass !== canonicalClass) {
@@ -583,20 +583,21 @@ For required push/merge/issue-close/release actions, execute without routine con
   parts.push(readFileSync(join(mosaicHome, 'AGENTS.md'), 'utf-8'));
 
   // USER.md (+ USER.local.md operator overlay, appended directly under the
-  // profile its base owns).
+  // profile its base owns). Fleet first start is Linux/systemd-owned and uses
+  // the no-follow reader at point of use. Standalone launches retain the
+  // portable tolerant path used on macOS and other supported hosts.
+  const fleetAgentName = process.env['MOSAIC_AGENT_NAME'];
   const user =
-    readOptionalInstalledIdentityContract(
+    fleetAgentName === undefined
-      mosaicHome,
+      ? readOptional(join(mosaicHome, 'USER.md'))
-      'USER.md',
+      : readInstalledIdentityContractAtPointOfUse(mosaicHome, 'USER.md').toString('utf8');
-      process.env['MOSAIC_AGENT_NAME'] !== undefined,
-    )?.toString('utf8') ?? '';
   if (user) parts.push('\n\n# User Profile\n\n' + user);
   const userLocal = readOptional(join(mosaicHome, 'USER.local.md'));
   if (userLocal.trim()) {
     parts.push('\n\n## Operator Overlay (USER.local.md)\n\n' + userLocal);
   }
 
-  const fleetIdentity = resolveFleetIdentity(mosaicHome, process.env['MOSAIC_AGENT_NAME']);
+  const fleetIdentity = resolveFleetIdentity(mosaicHome, fleetAgentName);
   if (!fleetIdentity.ok) {
     throw new Error(`Fleet communications contract unavailable: ${fleetIdentity.error}`);
   }